U.S. national team star Landon Donovan will miss the upcoming two World Cup qualifying matches because of a knee injury sustained in MLS play last weekend.

Donovan -- the national team's career leader in goals (49), assists (48) and matches started (130) -- injured the knee Saturday but felt good Monday and traveled to Miami to join his U.S. teammates. Upon arriving, he was further examined by U.S. trainers and underwent an MRI Tuesday.

Landon Donovan will miss the upcoming two World Cup qualifying matches because of a knee injury sustained in MLS play last weekend. (AP Photo)

Team officials did not disclose the nature of Donovan’s injury, saying only that he would return to Los Angeles for further treatment.

U.S. trainers also ruled out fellow midfielder Brek Shea because of an abdominal strain that has sidelined him since Sept. 29. Coach Jurgen Klinsmann did not immediately name replacements for Donovan and Shea.

The U.S. plays at Antigua and Barbuda on Friday and then plays host to Guatemala on Oct. 16 in Kansas City.

"It's unfortunate for Landon and Brek that they won't be able to play," said Klinsmann. "Landon was very optimistic over the weekend when his knee was feeling much better, but now he needs time to recover. We knew Brek was a question mark coming in, and now we have a clear picture of where he stands. We feel confident that the group we have will get the job done."

About 10 of the 24 players on the roster missed Tuesday’s morning practice for a variety of reasons — from jet lag to treatment of minor injuries. Outside of Shea and Donovan, the other 22 players trained later in the day.

The U.S., Guatemala and Jamaica all have seven points after the first four matches of Group A play in this qualifying round, and only two of the three will advance. Antigua and Barbuda has one point through four matches. For the U.S. to reach next year's regional finals, four points — a win and a tie — would seem to be the most probable requirement.